1. Field of the Invention
This invention relates to microprocessors. In particular, the invention relates to multifunction signals.
2. Description of Related Art
As demands for advanced features of microprocessor systems increase, system manufacturers face a challenging task to integrate as many functionalities as possible with lowest cost and highest performance. One of the common problems of system manufacturers is the need for flexibility in integrating devices into several platforms or environments.
Popular platforms or bus architectures include Peripheral Component Interconnect (PCI) and Industry Standard Architecture (ISA) buses. The PCI specification is provided by the Intel PCI Local Bus Specification Revision 2.2 published in February 1999. The PCI bus is a high performance bus that is intended as an interconnect mechanism between highly integrated peripheral controller components, peripheral add-in boards, and processor/memory subsystems. The ISA bus is a popular bus for lower bandwidth devices or peripheral components. Many platforms provide bus architectures that incorporate both types of bus. Interfacing devices, such as PCI-to-ISA bridge, exist to allow interfacing between the two buses. A peripheral device may have interface to both buses.
It is preferable that a peripheral device or processor provides functionalities that are flexible to a variety of personal computer (PC) manufacturers. Traditional techniques provide the different functionalities in different and separate pins. For example, a signal or pin is dedicated for one platform and another signal or pin is dedicated for another platform. This technique has a number of disadvantages. First, separate signals or pins increase pin count, resulting in complexity in packaging. Second, it reduces flexibility for PC manufacturers when the device or processor is integrated in different platforms.
Therefore, there is a need to have a multifunction functionality that is easy to use and flexible for PC manufacturers.
The present invention is a method and apparatus to provide multifunction to a device. A selector selects one of first and second functionalities based on a control setting. The selected one of the first and second functionalities is accessible at a pin of the device. A configuration mechanism is coupled to the selector to provide the control setting.